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Immunology 1 > 1) Innate Immunity > Flashcards

1) Innate Immunity Flashcards

1
Q

True or False. Innate immunity is specific.

A

FALSE. innate immunity is non-specific, meaning everyone’s response is nearly the same

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2
Q

What is the response time to innate immunity?

A

immediate

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3
Q

What are the cells involved with innate immunity?

A

1) phagocytes (macrophages)
2) neutrophils
3) natural killer cells

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4
Q

Is innate immunity preformed or takes time to develop?

A

preformed so it’s ready to go immediately

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5
Q

How does innate immunity get amplified? How is this different than adaptive immunity?

A

the cells are recruited to the site of injury in innate immunity. amplification in adaptive immunity is done by clonal expansion

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6
Q

What is known as the initial response to microbes that prevents, controls or eliminates infection of the host by many pathogens

A

innate immunity

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7
Q

Molecular structures that are produced by microbial pathogens that are recognized by innate immunity

A

PAMPs (pattern-associated molecular patterns)

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8
Q

What PAMP is expressed by gram negative bacteria?

A

LPS (lipopolysaccharide)

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9
Q

Endogenous molecules that are produced by or released from damaged and dying cells

A

damage-associated molecular patterns (DAMPs)

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10
Q

What recognizes PAMPs?

A

pattern recognition receptors on host cells

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11
Q

What pattern recognition receptor binds to LPS?

A

TL4 (toll-like receptor)

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12
Q

TL4 is found on the surface of which cells?

A

macrophages

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13
Q

What are some locations where toll-like receptors (TLR) are found?

A

1) cell membrane
2) inside endosomes
3) cytosol
4) all throughout the cell

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14
Q

Toll-like receptors are a subset of what?

A

pattern recognition receptors

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15
Q

The binding of PAMP to TLR leads to what?

A

signal transduction cascade that results in the activation of transcription factors NFkB and IRFs (interferon response factors)

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16
Q

What does the activation of NFkB lead to?

A

activates cell to produce pro-inflammatory cytokines

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17
Q

What does the activation of IRF lead to?

A

production of Type I IFN (interferons), which are cytokines that have antiviral properties

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18
Q

What is an inflammasome?

A

It’s an intracellular pattern recognition receptor complex that leads to the formation of IL-1, which is an important cytokine that leads to inflammation

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19
Q

Autoinflammatory syndromes are due to dysregulated activation what?

A

inflammasome gets a gain-of-function mutation that leads to excessive expression of IL-1, causing recurrent attacks of fever and localized inflammation

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20
Q

What is the treatment for autoinflammtory syndromes?

A

IL-1 antagonists

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21
Q

What are the different types of physical barriers (3)?

A

1) mechanical
2) chemical
3) microbiological

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22
Q

What areas of the body is considered epithelial barriers?

A

skin, gut, lungs, eyes and nose

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23
Q

What type of cellular junctions do epithelial cells have?

A

tight junctions that prevent microbes from passing through

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24
Q

How does ciliary action work as a mechanical barrier to infection?

A

the respiratory tract is lined with cilia that are constantly pushing mucous up and out, thus preventing pathogens from attachment and invasion

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25
Q

What mechanical barrier do skin and gut have along with epithelial cells?

A

longitudinal flow of air or fluid

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26
Q

What do epithelial cells produce that can impede entry of microbes?

A

anti-microbial chemicals

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27
Q

What are defensins and cathelicidins, what functions do they have?

A

anti-microbial peptides produced by epithelial cells; these are toxic to microbes and can activate leukocytes to promote inflammation

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28
Q

What do lysozymes do?

A

they break down peptidoglycans (found in bacterial cell walls)

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29
Q

What is microbiome?

A

includes all of the commensal bacteria that normally reside in/on epithelial barriers, can also include viruses, fungi and protozoa

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30
Q

What are the three professional phagocytes?

A

1) neutrophils (polymorphonuclear leukocytes, PMN)
2) monocyte/macrophage (mononuclear phagocyte)
3) dendritic cells

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31
Q

Which phagocytes are the first to respond to pathogens?

A

PMN (neutrophils)

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32
Q

What is the life expectancy of neutrophils?

A

short-lived (24-48 hours)

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33
Q

What are monocytes derived from and where?

A

hematopoietic stem cells in bone marrow

34
Q

What is the life expectancy of macrophages?

A

long-lived (months)

35
Q

Where are macrophages found?

A

in all tissues

36
Q

What are dendritic cells?

A

they are antigen presenting cells. they phagocytose pathogens or antigens and migrate to lymph nodes to present antigens to lymphocytes

37
Q

What is the first step in generation of an immune response?

A

phagocytosis

38
Q

True or false. macrophages phagocytize dead neutrophils

A

True. they phagocytize them to prevent them from releasing toxic chemicals

39
Q

What leukocyte makes up the most of circulating leukocytes?

A

PMN, about 59%

40
Q

What are the steps to phagocytosis?

A

1) target recognition
2) binding and signaling
3) actin rearrangement
4) engulfing leading to zippering or sinking of the particle into the phagocyte
5) destroy particle by breaking it down

41
Q

What are opsonins?

A

soluble proteins that recognize phagocytic targets and coats them

42
Q

How do opsonins mediate phagocytosis?

A

they have specific receptors that are recognized by phagocytes. once they coat a target particle, phagocytes bind to them. opsonized targets are engulfed much more efficiently than non-opsonized targets

43
Q

What are the major opsonins in blood?

A

complement component C3b and antibody IgG

44
Q

What are the anti-microbial functions of phagocytic cells (4)?

A

1) acidification
2) toxic oxygen-derived products
3) toxic nitrogen oxides
4) lysozymes

45
Q

Describe the events after engulfment of target particle by a phagocyte

A

once engulfment of particle occurs, it is called a phagosome, which fuses with a lysosome to form a phagolysosome

46
Q

What is the pH of a phagolysosome and what is its significance?

A

3.5-4.0

bacteriostatic or bactericidal

47
Q

What is the function of NADPH oxidase?

A

they generate ROS that are toxic to microbes

48
Q

Hypohalite OCl- is a type of …

A

toxic oxygen-derived products

49
Q

What happens when someone has deficiency in expression or function of NADPH oxidase?

A

chronic granulomatous disease (CGD). inability to generate ROS which means defect in killing of intracellular bacteria, leading to increased susceptibility to bacterial infection

50
Q

When is toxic nitrogen oxides produced?

A

nitric oxide is produced from activated macrophages leading to release of proinflamatory cytokines such as TNF

51
Q

What is the most important activator for macrophages?

A

IFN- gamma

52
Q

What are some characteristics of natural killer cells?

A

1) large, granular lymphocytes
2) non-specific
3) kill virus-infected cells and certain tumor cells

53
Q

When do NK cells know when a cell has been infected?

A

cell is lacking Class I MHC

54
Q

What receptor activates NK cells to kill?

A

CD16 (Fc-gamma RIII)

55
Q

CD16 is expressed by which cell type and what does it bind? What is this process called?

A

CD16 is expressed by NK cells and it binds to IgG, which binds to antigens expressed on an infected cell. This process is antibody-dependent cell-mediated cytotoxicity (ADCC)

56
Q

Which cytokine is released by macrophages that activates NK cells?

A

IL-12

57
Q

IL-12 stimulates NK cells to produce and release what cytokine?

A

IFN -gamma, which in turn stimulates macrophages

58
Q

Innate lymphoid cells are located …

A

at barriers and they make cytokines

59
Q

Majority of our bodies’ innate lymphoid cells are alpha-beta, the others are…

A

1) gamma-delta T cells - these cells are monospecific located in skin and mucosa (epithelial barriers)
2) NK T cells have characteristics of both NK cells and T cells, produces cytokines, and some recognize lipid antigens

60
Q

What are the three functions of complement?

A

1) pores in the cell surface –> death by osmotic lysis
2) opsonization
3) stimulate inflammatory reactions

61
Q

Which complement molecules recruit and activate leukocytes?

A

C3a and C5a

62
Q

Which complement molecule is involved with opsonization?

A

C3b

63
Q

What are the three pathways of complement?

A

1) alternative (spontaneous)
2) classical (antibody)
3) lectin (sugars on pathogens)

64
Q

Which two antibodies can activate the classical complement pathway?

A

IgG and IgM

65
Q

Can stand-alone antibodies activated complement?

A

NO, antibodies must be bound to surface of pathogens in order to activate complement

66
Q

Which antibody is more efficient, IgG or IgM?

A

IgM (only 1 IgM is needed while 2 IgGs are needed)

67
Q

What is the recognition component of classical pathway?

A

C1q

68
Q

Which complement component is spontaneously cleaved in alternative pathway?

A

C3 –> C3a (anaphylatoxin) + C3b (moves on to next step)

69
Q

True or False. All 3 complement pathways lead to the same effector functions.

A

TRUE

70
Q

What causes paroxysmal nocturnal hemoglobinuria?

A

uncontrolled activation of complement system (lack DAF and CD59)

71
Q

All 3 complement pathways converge to which complement molecule?

A

C3 –> cleaved by C3 convertase

72
Q

Deficiency in classical pathway (C1, C2, C3) will lead to…

A

immuno-complex disease such as lupus

73
Q

Deficiency in mannose-binding lectin pathway will lead to…

A

susceptibility to bacterial infections in childhood

74
Q

Deficiency in alternative pathway (factor D and factor P) will lead to…

A

susceptibility to bacterial infections with Nisseria and pyogenic (pus-forming) bacteria, but no immuno-complex disease

75
Q

Deficiency in C3 will lead to …

A

similar to deficiency with alternative pathway, but sometimes with immuno-complex disease

76
Q

Deficiency in MAC (membrane-attack components, C5-C9) will lead to …

A

susceptibility to Nisseria bacteria only (N. meningitis and N. gonorrhoeae)

77
Q

What are cytokines?

A

proteins made by cells that affect the behavior of other cells, mode of communication for immune system

78
Q

TNF, IL-1, and IL-6 are all what kind of cytokines?

A

pro-inflammatory

79
Q

IFN-alpha and IFN-beta are both which kind of cytokines?

A

Type I. Anti-viral

80
Q

What biological actions do type 1 IFNs have?

A

1) inhibit viral replication via a paracrine action
2) enhance cytolytic capability of NK cells
3) increase cellular expression of class I MHC molecules

Immunology 1 (9 decks)

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